Blackjack House Edge: How Every Table Rule Changes the Number
"Blackjack has a 0.5% house edge" is true of a specific table with specific rules, played perfectly. Change the rules and it ranges from about 0.26% to over 2% — a spread wider than the difference between blackjack and roulette.
Since the rules are printed on the felt, you can price a table before you sit down. Here's the table to price it with.
The baseline
Start from a common shoe game: six decks, dealer stands on soft 17, blackjack pays 3:2, double on any two cards, double after split allowed, no surrender. Perfect basic strategy against those rules gives a house edge of about 0.40%.
Every rule below adjusts that number.
The rules that help you
| Rule | Effect |
|---|---|
| Single deck (vs six) | −0.48% |
| Double deck (vs six) | −0.19% |
| Dealer stands on soft 17 | −0.22% |
| Late surrender allowed | −0.07% |
| Double after split allowed | −0.14% |
| Re-split aces allowed | −0.08% |
| Double on any number of cards | −0.24% |
| Six-card Charlie (6 cards without busting wins) | −0.16% |
| Early surrender (very rare) | −0.62% |
The rules that hurt you
| Rule | Effect |
|---|---|
| Blackjack pays 6:5 | +1.39% |
| Blackjack pays 1:1 | +2.3% |
| Dealer hits soft 17 | +0.22% |
| Double on 10 and 11 only | +0.18% |
| Double on 9, 10, 11 only | +0.09% |
| No double after split | +0.14% |
| Eight decks (vs six) | +0.02% |
| No re-splitting | +0.03% |
| Dealer wins ties (rare, avoid) | +9% |
The one number that dominates
6:5 blackjack costs +1.39%.
That single rule change is larger than every other rule on both tables combined, larger than the entire gap between a good player and a bad one, and larger than the difference between blackjack and craps. It converts the best game in the casino into a mediocre one.
The mechanism is simple: you're dealt a natural blackjack roughly once every 21 hands. On a $20 bet, 3:2 pays $30 and 6:5 pays $24. That $6, once every 21 hands, is 1.39% of everything you wager.
Tables are legally required to state the payout, usually on the felt in small print. Check it every time. A 6:5 single-deck table is worse than a 3:2 eight-deck table, which is counterintuitive and true.
Pricing three real tables
Table A — six decks, S17, 3:2, DAS, late surrender. 0.40% − 0.22% − 0.14% − 0.07% = about 0.26% with the S17 baseline adjustment. Excellent; play this.
Table B — six decks, H17, 3:2, DAS, no surrender. 0.40% + 0.22% − 0.14% = about 0.48%. Normal and perfectly fine.
Table C — double deck, H17, 6:5, no DAS. 0.40% − 0.19% + 0.22% + 1.39% + 0.14% = about 1.96%. Marketed as a "player-friendly double-deck game". It's four times worse than Table A. Walk past it.
What these numbers assume
Perfect basic strategy. All of the above assumes you play every hand correctly. An average player making the usual mistakes — standing on soft 18 against a 9, hitting 12 against a 5, taking insurance — adds roughly 1.5% to 2% on top of whatever the table's rules give. For most players, their own play is a bigger factor than every rule on the felt.
Which puts the priorities in order:
- Learn basic strategy. Worth ~1.5%.
- Avoid 6:5 tables. Worth ~1.4%.
- Never take insurance or side bets. Worth a few tenths, and more in practice.
- Prefer S17, fewer decks, surrender, DAS. Worth a few tenths in total.
The first two are worth more than everything else put together, and both are free.
Insurance and side bets
Insurance is a separate bet that the dealer has blackjack, paying 2:1. The dealer has it about 30.8% of the time when showing an ace, and you need 33.3% to break even — a house edge of about 7.4%. Taking it with a good hand doesn't help: the bets are independent, and "protecting" a 20 is not a thing that happens.
Side bets — Perfect Pairs, 21+3, Lucky Ladies, Royal Match, Bust It — run 4% to 15%. They sit next to a 0.5% game and are placed with the same hand, which is exactly why they're offered.
Practising against real rules
Because the strategy changes with the rules, a strategy chart learned for one table is subtly wrong at another. That's the argument for learning from a solver rather than a chart.
Casino Trainer's blackjack solver is exact and composition-dependent — recursive dealer and player trees rather than a lookup — and the table rules are editable, with the house edge recalculated live as you change them. Switch to H17 and the four affected decisions change; drop to double deck and the doubling ranges change. You can see the 6:5 rule add 1.4% to the displayed edge the moment you toggle it, which is a more memorable way to learn that fact than reading it here.
Virtual credits only, no real-money play.
The summary
- Baseline six-deck game: ~0.40%.
- 6:5 blackjack: +1.39%. The one rule that matters more than all the others.
- Dealer hits soft 17: +0.22%. Common, tolerable.
- Fewer decks, surrender, and double-after-split all help, by a tenth or two each.
- Your own play is worth more than the felt. Basic strategy first.
Want to see the edge change as you change the rules? Get Casino Trainer — virtual credits only.
Want the correct play named for you, hand by hand? Get Casino Trainer — virtual credits only, never real money.